Magnetic catch



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April 15, 1969 MAGNETIC CATCH Filed May 27. 1966 Sheet -Z of s Z 5% m2WZ Nd United States Patent M 3,438,665 MAGNETIC CATCH Lloyd L. Anderson,Rockford, Ill., assignor, by mesne assignments, to Amerock Corporation,Rockford, III., a corporation of Connecticut Filed May 27, 1966, Ser.No. 553.403

The portion of the term of the patent subsequent to Nov. 22, 1983, hasbeen disclaimed and dedicated to the Public Int. Cl. Ec 19/16 US. Cl.292-2515 17 Claims ABSTRACT OF THE DISCLOSURE For holding the door of acabinet in a closed position, a magnetic catch mounted on the cabinetincludes a pair of pole plates disposed on opposite sides of a permanentmagnet and engageable with a strike on the door to hold the door closedwith magnetic force. Full face engagement of the poles plates with thestrike is insured in spite of misaline-ment between the plates and thestrike by utilizing a lever to mount the plates for bodily shifting inopposite directions and also for notation in their respective planes sothat engagement of the strike with the plates as an incident to initialclosing of the door will adjust the positions of the platesautomatically to compensate for any misalinement. To promote uniformholding force, a resiliently yieldable spring exerts a restraining forceon the plates to prevent the latter from being shifted out of theiradjusted positions as the door is opened repeatedly during service use.

This invention relates to a magnetic holding device such as a catch forholding the door of a cabinet closed and, more particularly, to a catchwhich includes two units, one being a strike and the other being amagnet assembly. In such a catch, the magnet unit is formed with apermanent magnet sandwiched between a pair of plates of magneticmaterial which engage the strike whereby the strike completes the fluxpath for the magnet unit and the two units are held togethermagnetically. To insure full face engagement of the plates with thestrike, the plates are supported on the magnet to shift bodily relativeto one another by substantially equal amounts in opposite directions andto rotate in their respective planes so that the plates automaticallyadjust as an incident to closing the door and thereby fully engage thestrike even though the two units themselves may be considerablymisalined.

The general object of the present invention is to provide a new andimproved magnetic holding device of the above character which produces asubstantially more uni form magnetic holding force than prior devices ofthis type and, at the same time, enables separation of the units withsubstantially the same pulling force during the service life of thedevice.

A related object is to achieve the foregoing by applying a restrainingforce to the plates so that the plates, having once been shiftedoppositely and rotated to proper adjusted positions by a mechanicalforce, will remain in the adjusted positions in spite of magnetic forceacting on the plates during normal separation of the units.

A more detailed object is to utilize a resilient element for producing africtional restraining force between the magnet and the plates toprevent the later from shifting and rotating under the influence ofmagnetic force.

The invention also resides in the particular construction used to mountthe plates for shifting and rotation in conjunction with theconstruction of the resilient element for producing the restrainingforce.

3,438,665 Patented Apr. 15, 1969 Other objects and advantages willbecome apparent from the following detailed description taken inconnection with the accompanying drawings, in which FIGURE 1 is a sideelevation of a magnetic catch embodying the novel features of thepresent invention and shown as mounted on a typical cabinet.

FIG. 2 is a plan view of the catch.

FIG. 3 is an enlarged cross-section take-n substantially along the line3--3 of FIG. 2.

FIG. 4 is a view similar to FIG. 3 showing the plates in shiftedpositions to accommodate misalinement of the strike in one plane.

FIG. 5 is a view similar to FIG. 2 showing the plates in rotatedpositions to accommodate rnisalinement of the strike in another plane.

FIG. 6 is an enlarged perspective view of a part which mounts the platesfor shifting and rotation.

FIG. 7 is an end view of the catch.

FIG. 8 is a longitudinal sectional View of another form of theinvention.

FIG. 9 is a view similar to FIG. 8 showing the plates in shiftedpositions.

FIG. 10 is a longitudinal sectional view of still another form of catchconstructed according to the invention.

FIG. 11 is a view similar to FIG. 10 showing the plates in shiftedpositions.

FIG. 12 is an end view on a reduced scale of the catch shown in FIG. 10.

As shown in the drawings for purposes of illustration, the invention isembodied in a magnetic catch employing a permanent magnet and adapted tohold a closure member in a closed position. A typical application of thecatch may be in connection with a cabinet where the permanent magnetunit 15 of the catch is mounted on a part of the cabinet frame such as ashelf 16 and the strike 17 of the catch is mounted on the cabinet door18.

In this instance, the magnet unit 15 is housed within a casing 19 madeof non-magnetic material and formed with a bottom supporting wall 20,upstanding side walls 21, and mounting wings 23 projecting outwardlyfrom the side walls, the casing being fastened to the underside of theshelf 16 by screws 24 passing through slots 25 (FIG. 2) in the mountingwings. The magnet unit is positioned between the side walls and includesa permanent magnet wafer 26 sandwiched between flat pole plates 27 and28 of magnetic material lying against the two poles of the magnet andprojecting beyond the magnet to present edges or pole faces 29 whichabut the strike 17. The latter is a flat plate of magnetic materialfastened to the inside of the door 18 by a screw 30. Thus, the strikecompletes the flux path of the magnet 26 whereby the path extends fro-mthe magnet through one pole plate 27 to the strike 17 and back to themagnet through the other pole plate 28. As a result, the strike is heldagainst the pole faces 29 and the door is retained in a closed positionby the magnetic force. By rounding the pole faces on a full radius asshown most clearly in FIG. 3, a more consistent holding force isachieved than when the pole faces are square or semi-radiused.

For a permanent magnet of given strength, the force with which the catchholds the door 18 closed depends in large upon whether or not the polefaces 29 of the magnet unit 15 are in full face engagement with thestrike 17. Anything less than full face engagement introduces an air gapin the flux path and reduces the magnetic holding force. To insure fullface engagement of the pole faces 29 with the strike, the plates 27 and28 are mounted to shift bodily by substantially equal amounts inopposite directions and also to rotate in their respective planes. Thus,if the strike 17 is not at a. degree angle with the pole faces 2%, oneof the plates will shift in one direction and the other plate will shifta corresponding distance in the opposite direction, as shown in FIG. 4,until the two pole faces lie in the same plane as the strike. Similarly,should the strike and the pole faces be misalined along the longitudinalaxis of the latter as illustrated in FIG. 5, the plates will rotate inunison and in the same direction to assume a position in which the polefaces engage the strike along their entire length. In mostinstallations, both types of motion are likely to occur due to factorssuch as cabinet warpage and imprecise mounting of the magnet unit andthe strike 17.

The present invention contemplates a new and improved catch in which arestraining force is applied to the pole plates 27 and 28 to hold thelatter in their shifted and rotated positions after the pole faces 29once have become properly positioned relative to the strike 17 so thatsubstantially the same manual pulling force is required to separate theplates and the strike throughout the service life of the catch. To theseends, a resilient element 31 presses the plates 27 and 28 into matingcontact with the surfaces of the magnet 26 and presses the plate 28 intocontact with the surface of the bottom wall with sufficient force todevelop enough friction between the surfaces and the plates to resistshifting and rotation of the latter under the influence of magneticforce ap plied to the plates as when the door 18 is pulled from a closedto an open position. Since the plates thus are held in their initialadjusted positions, they do not peel away from the strike as the door isopened and, as a result, there are only small variations in the forcenecessary to pull the door open each time.

Herein, the plates 27 and 28 and the magnet 26 are fastened to thecasing 19 by an upright pin 32 projecting loosely through a hole 33 inthe magnet and holes 34 in each of the plates, the pin also extendingthrough the bottom wall 20 of the casing and being formed with anenlarged head 35 bearing against the bottom wall. To mount the platesfor bodily shifting in opposite directions and for rotation in theirrespective planes, a lever in the form of a tubular member 36 istelescoped over the pin and projects into the holes 34 in the plates. Asshown most clearly in FIGS. 3, 4 and 6, the tubular member is formed inthe shape of a pair of truncated cones 37 joined at their smaller endsto present an annular surface or edge 38 which rockably engages the pinnear the mid portion of the latter. The larger ends of the cones looselysurround the pin and engage the edges of the holes in the plates. Thus,when the strike 17 is alined as shown in FIG. 4, the lower plate 28 isengaged first and is pushed rearwardly upon initial closing of the door18. The rearward movement of this plate, acting through the tubularmember 36, produces a corresponding but opposite movement of the upperplate 27 and results in full face engagement of the pole faces 29'withthe strike. In addition, the plates will rotate in unison about the axisof the pin and will assume the positions shown in FIG. 5 when the dooris initially closed if the strike should be misalined along thelongitudinal axis of the pole faces.

In this instance, the resilient element 31 comprises a so-called starspring formed with a central portion 39 (FIG. 2) encircling the pin 32and bearing against the underside of a head 40 on the upper end of thepin. Radiating outwardly from the central portion of the spring 31 are aplurality of spaced legs 41 flexed into pressing engagement with theupper plate 28 and distributing the spring force over a substantial areaof the magnet unit 15. An additional pair of spring legs 42 are madeslightly longer than the legs 41 and project through slots 43 (FIGS. 1and 2) formed in the side walls 21 of the casing 19 to prevent thespring from rotating about the axis of the pin. With this arrangement,the plates adjust themselves for full face engagement of the pole faces29 with the strike 17 as an incident to the initial closing of the door,and the spring 31 develops enough friction between the plates, themagnet 26, and the bottom wall 20 of the casing to hold the plates intheir adjusted positions in spite of the magnetic force which acts onthe plates as the door 18 is pulled open.

A second form of the catch is shown in FIGS. 8 and 9 with the partscorresponding to those of the first embodiment being indicated by thesame reference numerals. In this instance, a pin 44 is formed with anannular head 45 around its mid-portion, and a cylinder 46 is telescopedover the pin and fulcrumed on the bead to form the pivot lever for theplates 27 and 28. At its ends, the cylinder 46 is formed with enlargedannular lips 47 which project into the holes 34 in the plates and engagethe edges of the holes. Thus, when the strike 17 engages one of theplates as shown in FIG. 9, this plate moves rearwardly thereby rockingthe cylinder about the bead 45 on the pin 44 to force the other plate inthe opposite direction and into engagement with the strike. As in thefirst em bodiment, the plates rotate about the axis of the pin in orderto accommodae misalignment of the strike along the longitudinal axis ofthe pole faces 29. The spring 31 for applying the restraining force isidentical to the spring employed in the first form of the catch.

Still another embodiment of the invention is illustrated in FIGS. 10 to12 and employs a modified spring construction and a different type of apivot lever for mounting the pole plates 27 and 28. In this embodiment,the magnet unit 15 is held in the casing 19 by tabs 48 turned inwardlyfrom the front and rear edges of the side walls 21 of the casing. Thetabs abut the forward and rear sides of the permanent magnet 26 to holdthe latter snugly in the casing while the corners of the pole plates areformed with notches 49 (FIG. 12) to accommodate the tabs. These notchesare of such size that the tabs 48 do not interfere with adjustment ofthe plates.

Mounting the plates 27 and 28 for rotation and bodily shifting is a pin50 formed with an enlarged rounded mid-portion 51 pivotally engaging theedges of the hole 33 in the magnet 26 and formed with smaller roundedends 52 pivotally socketed in the holes 34 in the pole plates. Theplates are free to rotate about the end portions 52 of the pin and thelatter pivots about its midportion 51 to enable shifting of the platesby equal amounts in opposite directions.

In this instance, the spring 54 for applying the restraining force tothe plates 27 and 28 is a strip of resilient material depressedintermediate its ends to form a pair of bowed wings 55 extending inopposite directions from a curved central portion 56. The outer endportions of the wings are flexed beneath inwardly projecting tangs 57struck from the side walls 21 of the casing 19 so that the centralportion of the spring overlies and bears downwardly on the central areaof the plate.

From the foregoing, it will be apparent that by employing a spring inconjunction with the shiftable and rotatable plates, the latter may beadjusted as an incident to the initial use of the catch and thefrictional restraining force will hold the plates in their adjustedpositions during normal service use so that pull variations are reduced.In addition, if the permanent magnet is of the type compounded withrubber and likely to be bowed, or if the plates are slightly warped, thespring will exert a constant force against the magnetic sandwich tendingto flatten the parts into mating contact. Such flattening actioneliminates air gaps introduced by improper mating and thereby results inincreased magnetic performance.

I claim as my invention:

1. In a catch, the combination of a support, a permanent magnet havinggenerally flat parallel surfaces at the poles thereof, first and secondgenerally flat plates of magnetic material lying against said surfacesand constituting pole pieces for said magnet, said magnet and saidplates being disposed on one side of said support with said first platebearing against the surface of the support, said magnet and said plateshaving alined holes near the central portions thereof, a pin fastened tosaid support and projecting through said holes to hold said magnet andsaid plates on the support, a tubular member telescoped over said pinand fitting loosely within the hole in said magnet, said tubular memberbeing fulcrurned intermediate its ends on said pin near the mid-portionof the latter and having opposite ends telescoped into and fulcrumed inthe holes in said plates thereby interconnecting the plates and causingthe latter to shift relative to one another by substantially equalamounts in opposite directions and to rotate about the axis of said pinwhen a force of predetermined magnitude is applied to the edges of theplates, and a resilient element engaging said second plate andcontinuously pressing the plates into mating frictional contact with thesurfaces of said magnet and pressing said first plate into frictionalcontact with the surface of said support with sufficient force todevelop enough friction between said plates and said surfaces to resistshifting and rotation of the plates when force of less thanpredetermined magnitude is applied to the edges of the plates.

2. A catch as defined in claim 1 in which said tubular member comprisesa pair of truncated cones having their smaller ends joined together nearthe mid-portion of said pin to form an annular rocking surface fulcrumedon the pin, the larger ends of the cones loosely surrounding said pinand engageable with the edges of the holes in said plates whereby saidannular surface rocks about said pin 'when force of predeterminedmagnitude is applied to the edges of the plates.

3. A catch as defined in claim 2 in which said pin has an enlarged headat the end adjacent said second plate, and said resilient elementincludes a spring having a cen tral portion encircling said pin andbearing against said head, said spring having legs projecting outwardlyfrom said central portion and stressed into engagement with said secondplate at spaced points thereon to distribute the force applied by thespring over a substantial area of said plates, said magnet, and saidsupport.

4. A catch as defined in claim 1 in which said pin has an enlargedmid-portion and smaller end portions, and said tubular member comprisesa hollow cylinder telescoped over said pin and fulcrumed on saidmid-portion, said cylinder having end portions loosely surrounding theend portions of said pin an engageable with the edges of the holes insaid plates.

5. A catch as defined in claim 4 in which said pin has an enlarged headat the end adjacent said second plate, and said resilient elementincludes a spring having a central portion encircling said pin andbearing against said head, said spring having a series of legs radiatingoutwardly from said central portion and stressed into engagement withsaid second plate at various points thereon to distribute the forceapplied by the spring over a substantial area of said plates, saidmagnet and said support.

6. In a catch, the combination of, a support, a permanent magnet havinggenerally flat parallel surfaces at the poles thereof, two generallyflat plates of magnetic material lying against said surfaces andconstituting pole pieces for said magnet, said magnet and said platesbeing disposed on one side of said support with one of the platesbearing against the surface of the support, said magnet and said plateshaving alined holes near the central portions thereof, means projectinginto said holes to interconnect said plates and to cause the latter toshift bodily by substantially equal amounts in opposite directionsrelative to one another while leaving the plates free for rotation intheir respective planes when force of predetermined magnitude is appliedto the edges of the plates, and yieldable means engaging the other ofsaid plates and continuously pressing the plates into mating frictionalcontact with the surfaces of said magnet and pressing said one plateinto frictional contact with the surface of said support under a forceof sufficient magnitude to develop enough friction between said surfacesand said plates to resist shifting and rotation of the plates as anincident to the application of force less than predetermined magnitudeto the edges of the plates.

7. A catch as defined in claim 6 in which said interconnecting meanscomprises a pin projecting into said holes in said magnet and saidplates, said plates being fulcrumed intermediate the ends of said pin toshift simultaneously in opposite directions relative to one another.

8. A catch as defined in claim 7 in which said interconnecting meansfurther includes a tubular member telescoped over said pin, said tubularmember having opposite ends telescoped into and fulcrumed in the holesin said plates and being fulcrumed intermediate its ends on said pm.

9. A catch as defined in claim 8 in which said pin has a circumferentialbead formed thereon between its ends, and said tubular member comprisesa hollow cylinder loosely telescoped over said pin and fulcrumed on saidbead.

10. A catch as defined in claim 7 in which said pin has an enlarged headat the end adjacent the other of said plates, and said yieldable meanscomprises a resilient element acting between said head and the other ofsaid plates and producing frictional contact between said surfaces toresist movement of said plates.

11. A catch as defined in claim 7 in which said pin has an enlarged,rounded mid-portion pivotally engaging the edges of the hole in saidmagnet, and smaller rounded ends pivotally socketed in the holes in saidplates.

12. A catch as defined in claim 11 further including a pair of Wallsdisposed perpendicular to said support and extending alongside oppositemargins of said plates, said yieldable means comprising a resilientelement having a central portion bearing against said other plate andhaving a pair of wings extending in opposite directions from saidcentral portion and bearing against said walls.

13. A catch as defined in claim 12 further including tangs formedintegrally with each of said walls and projecting toward each other, thewings of said resilient element being stressed between said tangs andsaid other plate.

14. In a device for selectively holding first and second separable partsin a predetermined position relative to each other, the combination of,a support mounted on said lfirst part, a permanent magnet havinggenerally flat parallel surfaces at the poles thereof, two generallyflat plates of magnetic material lying against said surfaces and havingedges facing said second part, said plates and said magnet beingdisposed on one side of said support with one of the plates being incontact with the surface of the support, a member composed of magneticmaterial mounted on said second part and having a face adapted forengagement with the edges of said plates whereby the flux path of saidmagnet extends through said face and said edges to hold the face and theedges in rigid abutment, said magnet. and said plates having alinedholes therein spaced inwardly from said edges, means projecting intosaid holes to interconnect said plates and to cause the latter to shiftsimultaneously by substantially equal amounts in opposite directionsrelative to one another whereby a mechanical force adjusts the platesfor full face engagement of said edges with said face, and a springengaging the other of said plates and continuously pressing the platesinto frictional mating engagement with the surfaces of said magnet andpressing said one plate into frictional engagement with the surface ofsaid support to develop sufiicient friction between said surfaces andsaid plates for restraining such shifting under normal separation ofsaid first and second parts thereby to retain said plates in theiradjusted positions during service use of the device.

15. In a catch, the combination of, magnetic unit including a permanentmagnet and a pair of pole pieces disposed on opposite sides of saidmagnet, a strike unit adaped for engagement with said pole pieceswhereby said units are held together by magnetic force, means includinga pin interconnecting said pole pieces for bodily movement in oppositedirections relative to each other in response to mechanical forceapplied to the pole pieces as an incident to the strike unit moving intoengagement with the magnetic unit, and resilient means resistingmovement of said pole pieces when magnetic force of less magnitude thanthe mechanical force is applied to the pole pieces as an incident toseparation of the strike unit and the magnetic unit.

16. A catch as defined in claim 15 in which said pin is formed with arounded mid-portion pivotally engaging said magnet and smaller roundedend portions pivotally socketed in said pole pieces.

17. In a device for selectively holding first and second separable partsin a predetermined position relative to each other, the combination of,a case mounted on said first part, a permanent magnet having generallyflat parallel surfaces at the poles thereof, two generally fiat platesof magnetic material lying against said surfaces and having edges facingsaid second part, said plates and said magnet being disposed within saidcase with one of the plates being in contact with one surface of thecase, a member composed of magnetic material mounted on said second partand having a face adapted for engagement with the edges of said plateswhereby the flux path of said magnet extends through said face and saidedges to hold the face and the edges in rigid abutment, said magnet andsaid plates having alined holes therein spaced inwardly from said edges,a pin projecting into said holes to interconect said plates and to causethe latter to shift simultaneously by substantially equal amounts inopposite directions relative to one another while leaving the platesfree for rotation in their respective planes whereby a mechanical forceadjusts the plates for full face engagement of said edges with saidface, Said pin being formed with a rounded mid-portion pivotallyengaging said magnet and being formed with smaller rounded end portionspivotally socketed in the holes in said plates, and said case i ncludingresiliently yieldable means disposed adjacent and engaging the other ofsaid plates and continuously pressing the plates into frictional matingegagement with the surfaces of said magnet and pressing said one plateinto frictional engagement with said one surface of said case to developsufficient friction between said surfaces and said plates forrestraining shifting and rotation of the plates under normal separationof said first and second parts thereby to retain said plates in theiradjusted positions during service use of the device.

References Cited UNITED STATES PATENTS 2,837,366 6/1958 Loeb 292-25l.52,954,253 9/1960 Teetor 292-2515 3,057,650 10/1962 Ahlgren 29225l.53,174,786 3/1965 Wilson 29225l.5 3,287,051 11/1966 Anderson 292251.5

MARVIN A. CHAMPION, Primary Examiner.

EDWARD J. MCCARTHY, Assistant Examiner.

